1. Field of Application
This invention relates to tool chucks for attachment to power drills, power drivers and the like, to hold tools such as drill bits and driver bits, and more particularly to the type of tool chuck that is manually tightened without using a chuck handle.
2. Description of the Prior Art
A conventional tool chuck of the type having a turn ring rotatable with a chuck handle to extend and retract chuck claws involves a cumbersome handle operation, maintenance of the chuck handle under care and other inconveniences. To eliminate such disadvantages, a tool chuck has already been developed which has a turn ring rotated manually without using a chuck handle to tighten the chuck claws, and a locking device for preventing the chuck claws from loosening during an operation.
With the tool chuck having such a locking device, however, the tool will rotate idly to the detriment of an effective operation if the chuck claws impart an insufficient clamping force.
In order to obtain a strong tightening force, it is conceivable to increase the torque by reducing the rotation of the turn ring through a suitable reduction mechanism. However, this would give rise to the problem that the chuck cannot be operated quickly since the chuck claws are caused to slide at a reduced speed even when an inserted tool is not clamped by the chuck claws.